: : At first I also thought it was singular but figured you wordsmiths know better.

: : If you turn the sentence around it is:
: : A number of problems are/is there.
: : If "number" is singular it would take a singular verb--"is"-- since problems is the object of a prepositional phrase.

: : Knocking out the prepositional phrase and the sentence reads: "A number is there" or "There is a number" which sounds perfectly ok.

: : But using the singular sounds awkward: "There is a number of problems".
: : Help!!

: From the Chicago Manual of Style:

: Number as a collective noun takes a singular or plural verb depending on the article (definite the or indefinite a) that precedes it:

: The number of pizzas ordered this year has doubled.

: but

: A number of studies have shown that stuffing a pizza with spinach triples the edibility of that sinewy vegetable.